With the rapid development of electronic products, they are increasingly important in daily life. In order to meet the market demand in space-saving and portability, electronic devices are becoming increasingly lighter and thinner, which requires the size of various components of the electronic devices, especially the thickness of each component to become smaller and smaller. For example, as one of the standard equipped components of the electronic devices, camera modules have a development trend of becoming light and thin.
The structure of a conventional manufactured and processed chip on board (COB) camera module is formed by assembling a rigid-flex combination board, a photosensitive chip, a lens base, a motor drive, and a lens assembly. The electronic components are arranged on the surface layer of the circuit board, and the components do not overlap each other. Along with the requirement for high-pixel and ultra-thin modules, the imaging requirement for the camera module is getting higher and higher. Thus, the assembly is more difficult and device specifications are higher. At the same time, as the pixels are getting higher, the chip area will increase accordingly, and the corresponding passive components such as the driving resistors and the capacitors increase accordingly, that is, the size of the module increases.
The existing mobile phone camera module package structure contradicts the demands on the thin-type and miniaturization of the camera module for the mobile phone. Therefore, it is necessary to invent a compact camera module and a new-type package process thereof to meet the needs of product development.
For the camera module based on the existing technology, in order to have a good supporting effect, the holder of the conventional camera module has to have a large size and occupy a large space, thereby increasing the size of the entire camera module. If the size of the holder is reduced for reducing the size of the camera module, the supporting effect of the holder may be affected.
In addition, only the circuit board of the conventional camera module is disposed at the bottom of the camera module, which is relatively far from the elements that require energy supply such as the motor and the photosensitive chip. Such disposition not only consumes more energy-conducting elements, such as wires, but also fails to provide an adequate and proper location design for the elements constituting the circuit in the entire circuit arrangement of the camera module as required, causing that the space occupied by the elements constituting the circuit is not properly reduced. That is, if the relative positions between the circuit board and other elements of the camera module are properly arranged, the space occupied by the necessary circuit elements of the camera module may be further reduced, thereby further reducing the size of the camera module. Certainly, the width or thickness of the camera module may also be selectively reduced according to the market demands.
In the conventional camera module assembly process, electronic elements such as capacitors, resistors, and integrated chips are components that need to be assembled and welded one by one. The assembly process includes: covering a steel mesh on the surface of the circuit board, brushing solder paste, placing and attaching the electronic elements one by one to the corresponding positions and reflow baking at 230° C.
FIG. 1 in the accompanying drawings illustrates an IC element mounting form based on the existing technology, wherein 101 refers to the circuit board. 102 refers to an IC element on the circuit board, i.e., a pad. 103 refers to the soldering tin. 104 refers to an IC element (including capacitor, resistor, driver chip, DSP chip, etc.).
The solder paste printing precision and the electronic element attaching precision are much less than the manufacturing precision of the circuit board. In addition, the pin and baking process of the elements has the risks of assembly offset, poor processing accuracy or high thickness, affecting the performance of the module.
In particular, in the conventional camera module assembly process, a drive motor is included. The drive motor is an independently assembled component including a housing, an elastic piece, a magnet, a carrier, a coil, a holder, and other components. The assembly process of the drive motor is to assemble sequentially the housing, the elastic piece, the magnet, the carrier, the coil and other components to the holder, and then fix the components by glue or welding to complete the assembly of the drive motor. However, the precision of such assembly process is far less than the processing and manufacturing precision of the camera module. Neither the manual assembly nor the mechanical automatic assembly can achieve a mass and rapid assembly. In addition, poor assembly precision or high thickness makes the size of the camera module easily and greatly fluctuate, causing difficulty in ensuring the quality.
In addition, FIG. 4 in the accompanying drawings of the specification illustrates a schematic structural diagram of a camera module according to the existing technology, wherein the camera module includes a lens assembly 1, a carrier 2, a voice coil motor 3, an optical filter 4, a photosensitive chip 5 and a circuit board 6. The lens assembly 1 is connected to the carrier 2. The lens assembly 1 and the carrier 2 are located in the middle of the voice coil motor 3. The optical filter 4 is located between the photosensitive chip 5 and the lens assembly 1. The photosensitive chip 5 and the optical filter 4 are supported by the circuit board 6. It is worth mentioning that the voice coil motor 3 includes a drive coil 31 that surrounds the carrier 2. The assembly of the entire camera module with such structure has a conductive package with a large dimensional tolerance, and is poor in the reliability of its own strength and the connection strength.
Although the camera module has been widely used in the current camera module field, it still has many drawbacks.
First, in the process of fabricating the camera module, the motor needs to be welded to the circuit board after the assembly of the camera module is completed, to achieve the conductible connection of the motor. The process is complex, and many additional problems may be caused by this welding process. For example, the product qualification rate is likely to be affected by the quality of the completion of the welding. Besides, this welded connection is not secure and can be easily damaged during use and maintenance.
Next, since a holder is disposed between the motor and the circuit board, the connection between the motor and the circuit board needs to cross the holder. The connection not only occupies space, but also is weak in firmness.
Next, using the conventional process, the external welded electrical connection between the motor and the holder is more susceptible to the external environment. For example, dust may affect its connection effect and service life.
As handheld smart devices such as smart phones and tablets, as well as smarter and lighter wearable smart devices, and even various types of Networks of Things application devices are generalized, the various devices must be light and thin on the one hand in order to meet the market demand in space-saving and portability. On the other hand, high-precision in photography is also required to enable fast input, recording, observation and identification functions, such as the use of the intelligence eyewear for observing roads instantaneously to aid in navigation, face recognition, or the use of the smart watch to scan 3D barcodes for obtaining further information. Therefore, in addition to the necessity to minimize the volume to comply with the trend, the camera modules that are equipped on these devices also need to ensure high precision and accuracy at the same time, to provide stably high-resolution images that are indispensable on many device applications.
In manufacturing the camera module, based on the conventional COB (Chip on Board) process, the camera module is formed by assembling a rigid-flex board, a photosensitive chip, a microscope base, a motor drive, and a lens assembly. The electronic components are arranged on the surface layer of the circuit board, and the components do not overlap each other. Along with the requirement for high-pixel and ultra-thin modules, while the volume of the camera module is reduced, the imaging requirement for the camera module is getting higher and higher. Thus, the assembly is more difficult. At the same time, as the pixels are getting higher, the chip area will increase accordingly, and corresponding passive components such as the driving resistors and the capacitors increase accordingly. As a result, the size of the module often inevitably becomes larger and larger, which further contradicts the demands on the thin-type and miniaturization of the existing smart device camera module package structure. Therefore, a solution for a compact camera module or a new-type package technology is in an urgent need to meet the trend of product development.
Although the above conventional manufacture process has been widely used in the current camera module field, it still has many drawbacks. First, in the process of manufacturing the camera module, the motor needs to be welded to the circuit board after the camera module is assembled in the lens assembly motor assembly, to achieve the conductible connection of the motor. The process is complex, and many additional problems may be caused by this welding process. For example, the product qualification rate is likely to be affected by the quality of the completion of the welding. At the same time, this welding is limited by the small size and high precision of the target subject, which makes the welding connection insecure and can be easily damaged during use and maintenance.
Next, since a holder is disposed between the motor and the circuit board, the connection between the motor and the circuit board needs to cross the holder. The connection not only occupies space, but also is weak in firmness. In addition, using the conventional process, the external welded electrical connection between the motor and the holder is more susceptible to the external environment. For example, dust may affect its connection effect and service life. In addition, in order to have a good supporting effect, the holder has to possess a large size and occupy a large space, thereby increasing the size of the entire camera module. If the size of the holder is reduced for reducing the size of the camera module, the supporting effect of the holder may be affected.
In addition, only the circuit board of the conventional camera module is disposed at the bottom of the camera module, which is relatively far from the elements that require energy supply such as the motor and the photosensitive chip. Such disposition only consumes more energy-conducting elements, such as wires, but also fails to provide an adequate and proper location design for the elements constituting the circuit in the entire circuit arrangement of the camera module as required, causing that space occupied by the elements constituting the circuit is not properly reduced. That is, if the relative positions between the circuit board and other elements of the camera module are properly arranged, the space occupied by the necessary circuit elements of the camera module may be further reduced, thereby further reducing the size of the camera module. Certainly, the width or thickness of the camera module may also be selectively reduced according to the market demands.
Meanwhile, after the camera module assembly is completed, based on the conventional process, an electromagnetic shielding component is also needed to be mounted to ensure that the camera module does not affect electromagnetic wave sources or devices other than itself during the operation process, so as to ensure that the camera module still has extremely high precision in the case of a minimized volume. Unfortunately, in the conventional practice, a metal housing, a conductive cloth, or a conductive copper foil is wrapped and embedded in the outer portion of the camera module, and then connected to the ground terminal of the camera module using a conductive glue or a conductive tape. The assembly precision is far less than the processing and fabrication precision of the camera module. Neither the manual assembly nor the mechanical automatic assembly can achieve a mass and rapid assembly. In addition, poor assembly precision or high thickness makes the size of the camera module of the final production easily and greatly fluctuate, causing difficulty in ensuring the quality, let alone pursuing the aforementioned thinness, lightness and precision.
In addition, based on the existing technology, as shown in FIG. 5, the existing method generally is to mount an independent electromagnetic shielding element 96 to the outer portion of the camera module 90 in a wrapping or nesting way after the camera module 90 is assembled. The electromagnetic shielding element 96 usually adopts a metal housing, a conductive cloth or a conductive copper foil, etc. After wrapping or nesting the outer portion of the camera module 90, the electromagnetic shielding element 96 is connected to the ground terminal of the camera module 90 by using a conductive glue or a conductive tape, thereby achieving the assembly of the electromagnetic shielding element 96. However, the precision of such assembly is often far less than the precision of the camera module 90 during processing and fabrication. Due to the poor assembly precision or high thickness, the size of the finished product of the camera module 90 often fluctuates greatly and the quality is difficult to ensure. Meanwhile, regardless of manual wrapping or mechanized automatic wrapping, the current practice cannot achieve mass and rapid processing and assembly in the electromagnetic shielding element 96.